Electrophoretic display devices have been widely applied to electronic papers because the electrophoretic display devices have characteristics of bistable display paper-like effect, low cost and flexibility. In addition, the electrophoretic display devices can also be used in large scale display devices. However, it is difficult for the electrophoretic display devices to be driven by an easy and cost-effective driving method.
Conventionally, a direct driving method is used in an electrophoretic display device. In the direct driving method, each pixel is controlled by an external driving circuit. Thus, the direct driving method has a high cost, and is not applicable to the electrophoretic display device having great amount of pixels or the electrophoretic display device whose pixels are tightly packaged together. Additionally, an active matrix driving method is also used in the electrophoretic display device. In the active matrix driving method, an active matrix including a number of nonlinear elements such as transistors, diodes, or rheostats is formed on a substrate of the electrophoretic display device to control the pixels. The active matrix driving method is a well-developed technology and has been widely used in liquid crystal display devices. However, the active matrix driving method still has a high cost. Moreover, it is difficult to form the active matrix on a plastic substrate which is widely used in the electrophoretic display device.
Besides, the electrophoretic display device utilizes an electric field to control the movements of displaying particles, and thus there is not a specific controlling threshold voltage. In other words, even if the electric potential of the pixel electrode is at a low level the pixel corresponding to the pixel electrode would still displays. It is noted that, generally, the low level electric potential of the pixel electrode maybe mean that the pixel corresponding to the pixel electrode should be off. Therefore, the contrast of the electrophoretic display device using the direct driving method or the active matrix driving method will be decreased.
Accordingly, what is needed is to provide an electrophoretic display device having an easy driving method and a high contrast.